Process for extracting mineral oils with basic selective solvents



'i'ES PATE PROCESS FOR EXTBACTING MINERAL OILS WITH BASIC SELECTIVE SOLVENTS David R. Merrill, Long Beach, Calif., assignor to Union Oil Gompany of California, Lcs Angeles, Calif., a corporation of California T OFFIQE No Drawing. Application January 19, 1935, Serial No. 2,583

Claims. (01. 196-43) This invention relates to a method for exbricating oil at e gh temperatures p y d tracting oil with solvents; such oil may be vege- 1055 Of fu ural Oc u s. T e p e Of Organic table oils or animal oils, and relates particularly base of ac ds n t e Oil tends to catalyze this to the petroleum oils such as kerosene, gasoline p y e i t on- 5 and lubricating oils. The process relates par- I have discovered that all of these disadvanticularly to methods of solvent extraction of ta s y e avoided y either 0he of the petroleum oils with selective solvents which are lowing three procedurespolar in nature and highly reactive chemically. (i) The naphthenic acids present in the stock Such solvents are, for example, sulfur dioxide, to be t eated may be re ved Prior to Solvent a ne. chloraniline, ammonia, phenol, chlorextraction by washing with caustic soda and the 10 phenol and iurfural. organic bases may be removed by neutralizing Many of the petroleum stocks extracted conwith dilute sulfuric acid. Other bases and acids tain organic acids such as naphthenic acids. may be employed. Such procedures are well Many of such stocks contain basic compounds known as methods for removing n ph h nic such as quinoline, derivatives of quinoline, deacids and organic nitrogen bases. Material so 15 rivatives of the non-aromatic bases such as treated is then extracted with a y of e S01- those discovered by Dr. J. R. Bailey and reported vents above mentioned. The loss of the acidic in the Journal of the American Chemical Society, and basic solvents as salts, or of the aryl amines volume 52, pages 1239-1250 (1930), volume 53, as anilides or the loss of furf ral du to p y- 2 pages 3160-3164 (1931) and volume 55, pages -merization will either be obviated or materially 41454149 (1933). These organic acids and reduced. No loss of solvent will result from bases, because of their polar character, tend to chemical combination since the deleterious maconcentrate in the extract rather than the terial has been removed from the stock. raflinate phase in a solvent extraction operation. (2) The extract material produced by extrac- Stocks which contain naphthenic acids are tion with either of the above basic or acidic se- 25 kerosene stocks, gasoline stocks and lubricating lective solvents may be treated in the case of stocks. In extracting such stocks with basic the basic compounds with an inorganic base such solvents such as aniline, chloraniline and liquid as sodium hydroxide or carbonate, calcium or ammonia, these acids react with the solvents to magnesium hydroxide or other alkali material form salts, and at the high temperatures emto liberate the bound solvent from the naph- 30 ployed with some of these solvents, especially in thenic acids to form inorganic naphthenates and removing the solvent from the oil by distillation, the free selective solvent. The alkali material which may reach as high as 250 F. or more, is preferably added before substantial heating these acids may react with these arylamines to or" the extract phase occurs. In the case of form anilides. These reaction products are aniline and chloraniline substituted amides are 35 usually discharged with the extract causing a formed from salts of these bases due to the high loss of solvent. In using acidic selective solvents temperatures obtained during the stripping of such as chlorphenols and liquid sulfur dioxide, the solvent from the extract. By adding alkali the organic bases present in the stock may react material at a point in the recovery system used with these acidic materials to cause a loss of for the recovery of s ect Solvent from the 40 solvent into the extract in the form of salts or extract at which only Salts are present and at a other r a ti products temperature below that at which amide forma- This loss in both of these cases Occurs even tion occurs, the amide formation can be prevented.

though relatively high temperatures and vacuum are employed upon the extract containing (3) A third modlficatmn is to remove the solvent from the extract phase without particular s 2 recovfry of Solvent. In the f regard to temperature other than that required we mm 8 Ede eanu process m Operatmg in solvent recovery, and then to contact the reupon California kerosenes and gasolines, residual Covered extract 011 containing amides with S0di Sulfur dioxide is fOllIld in the extract even after um hydroxide or any of the above mentioned st pp n u d v uum Neutralization of alkaline materials to hydrolyze the amide, and

t es e t ts W Sodium Y X as been recover the selective solvent. This is convenient- ;found essential to remove residual sulfur di- 1y done by introducing into the base of the extract oxide. evaporator an amount of caustic soda or other In us furfulal in S01Vent t e t On 0f alkaline material sufiicient to hydrolyze the con- 55 tained amides and react with the salts to liberate the selective solvent.

In applying this invention to the selective solvent process employing acidic materials such as phenol, chlorphenol, sulfur dioxide, instead of using the basic materials above mentioned, dilute acid such as acetic acid or oxalic acid or other organic acid forming an oil soluble salt of the base having low volatility is employed. Instead of using organic acids, dilute inorganic acids, such as hydrochloric acid or sulfuric acid may be employed. The action is analogous to that previously referred to in the case of the basic selective solvents, the reaction being to form salts of the bases present in the oil and to release the selective solvent which had formed salts of these bases. These acids may be introduced into such portion of the apparatus as, for instance, into the base of the evaporator to cause a release of the bound selective solvent in the extract.

The above matter is not to be taken as limiting my invention but merely as illustrating the best method of carrying it out, and many Variations of said invention will suggest themselves to those skilled in the art.

I claim:

3.. In a process of separating mineral oil into fractions relatively more parafiinic in character and relatively less paraffinic in character than the original oil with a selective solvent which is basic in character and reactive with acid constituents present in the oil, the step of neutralizing said acid constituents with an alkali prior to extraction of said oil with said basic selective solvent.

2. A process for the separation of mineral oil containing acidic constituents into fractions,

v which comprises treating said oil with an alkali to remove said acidic constituents and then extracting said alkali treated oil into a plurality of fractions with a selective solvent adapted to separate said oil into fractions relatively more parafiinic in character and less parafiinic in character than the original oil, said selective solvent being further characterized by being chemically reactive with the said acidic constituents removed from said mineral oil by treatment with alkali.

3. A process for the solvent fractionation of mineral oil containing acidic constituents of the character of naphthenic acids which comprises treating said oil with an alkali to remove said acid constituents and then extracting said alkali treated oil with a selective solvent of the basic type such as aniline into fractions relatively more paraffinic in character and relatively less paraffinic in character than the original oil.

4. A process for the separation 'of mineral oil containing acidic constituents into fractions with a basic selective solvent adapted to dissolve the non-paraffinic fractions of the oil and further characterized by being reactive with the acidic constituents of the oil which comprises treating said oil with an alkali to convert said acidic con stituents into salts which are not reactive with said selective solvent and then extracting said alkali treated oil with a selective solvent.

5. A process according to claim l in which the reaction products produced by treating the oil with said alkali are removed prior to extraction of the oil with the selective solvent.

DAVID R. MERRILL. 

